How do zombies actually become zombies? There are many types of outbreak and it is commonly accepted that a zombie outbreak starts with a virus (either Solanum or Rage). Solanum is not waterborne or airborne and will die without a host. There is no cure for the Solanum virus and once contracted it is 100% fatal. Whether contracting the Rage virus is curable or not is still up for debate as various sources describe different levels of infection and speed at which one turns into a zombie when infected. Exactly where these viruses originate from is also still hotly debated as there are several explanations but no one can agree on an exact answer.
Stage one: Transference of the virus.
A victim can become infected by both Rage and Solanum viruses by: being bitten or scratched by an infected zombie, coming in direct contact with a zombie’s bodily fluids, being splattered by a zombie’s remains, or from brushing an open wound against a zombie’s. Accidental or purposeful ingestion of infected zombie flesh results in permanent death rather than infection. If bitten, the only option is to immediately remove the limb thus preventing the virus from reaching the brain. However, given the speed at which the heart pumps blood around the body and the psychological willpower required to do this, the chances of successfully surviving are incredibly slim. If bitten anywhere else than a limb, the victim is doomed.
Stage two: Succumbing to infection.
Solanum virus. The signs of infection will become obvious within a matter of hours, the symptoms include a headache, fever, chills, slow pulse, shallow breathing and eventually coma. During this coma the victim effectively dies and is reanimated as the walking dead. The length of the coma varies from a few minutes to several hours. As soon as a victim is infected the Solanum virus will replicate in the victim’s brain (specifically the frontal lobe) and start to shut down bodily functions such as the heart and lungs, and will remove all emotions and sense of pain. All trace of humanity is erased from the victim permanently.
Rage virus. Once infected the victim will become a zombie within a matter of seconds. It is paramount that you act quickly to avoid further spread of the virus.
If an infected person chooses suicide, then they must make sure that they destroy their brain in order to prevent reanimation (so jumping from a building will not prevent that person from returning as a zombie, albeit a crawler). Anyone killed after being infected should have their destroyed and body burnt to prevent further spread of the virus.
Stage three: Transformation.
Once they “awaken” from their coma, the victim is no longer human and is now a zombie. In the case of the Rage virus there is no coma and the transition to zombie is almost immediate. Once alert, the zombie will be unresponsive to most stimulus and will only be hunting for living creatures to eat and infect.
In both instances the victim’s brain is transformed and only one basic instinct will remain: to hunt and consume the living. However, there is a big difference between how both types of virus survives. A Rage zombie will only stay active for as long as it has living flesh to consume and once it stops feeding it will eventually starve and die. There is still no answer for how a zombie infected with the Solanum virus continues moving about but it is understood that the Solanum virus changes each of the victim’s infected cells into an independent cell that produces its own oxygen which circulates through the zombie’s body thus removing the need for food, water, or even air. Consuming living flesh is a reflexive action but the Solanum virus does not require it to survive and anything eaten remains inside the zombie’s guts until it is passed through from the zombie eating more.
Stage four: Decay & Decomposition.
Once reanimated as the walking dead, the cells of the infected start to die resulting in the decomposition of organs and flesh. Rage zombies do not decay as they are infected humans (read about the zombie types for more) and they simply continue to live until they can no longer find anything to eat and then starve to death. Solanum infected zombies however will continue to be active for many years despite their flesh rotting. The biological process of the body repairing cells no longer occurs and the result is an unholy stench and horrific appearance. Since the infected zombie has an incredibly high level of toxicity in its flesh, and the bacteria that usually speeds up decomposition is killed by the virus the rate of decomposition is much slower than usually found in a dead body.
Further reading: Infection with other species.
All animals apart from humans can instinctively detect the Solanum and Rage viruses and will immediately flee from it as fast as possible. Both viruses are fatal to all living creatures and if an animal contracts either virus it will die within a matter of hours but not reanimate as walking dead – this is specific only to humans. There is no chance of an insect biting an infected victim and then biting an uninfected person to pass on the virus because all insects can detect and will flee from anything that has been infected. This is why during a zombie apocalypse if there are no sounds of nature (birds, crickets, flies, farm animals, etc) then you will know that the infected are nearby.